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[Dave DND]

Much has been said on the forum about the internal rechargeable powersounder battery and its failings, but knowing that there is a wealth of expertise on here, I have a few thoughts, and was wondering if any of you have similar opinions or thoughts?

One of the symptoms, sorry, let me rephrase that, one of the indications, that something is wrong with the internal powersounder battery is when the internal voltage drops below its designated threshold and its monitoring circuit will start to emit a few beeps.

In my experience, this usually indicates either a faulty powersounder battery, or, more significantly, a low voltage on the main car battery - (Go with me on this for a minute ) If the Main Battery is also dipping below its threshold voltage, although it may be able to crank and start the car and appear that all is well, the monitored voltage may still be below what the siren is expecting, and it may start to beep (sometimes).

This is not an uncommon scenario when cars are left for long periods of time and the battery is not keeping up its charge as simply not being driven enough.

In order to try and determine why the battry packs are failing, I have had a thought - could be utter rubbish, but this is why I`m asking for some thoughts.

If the main car battery is left to deteriorate by insufficient charge, and constant short journeys, we all know that it will eventually knacker itself fairly quickly - SO . .  If it did, and was constantly left in a poor state, what effect would that have on a secondary battery that was connected directly to it? ie: powersounder battery?  Would the constant lower voltage of the main battery cause any form of loss in voltage of the powersounder battery to a point where prolonged heat and current could become an issue as the two tried to charge each other - and if so, would sustained exposure to this cause the powersounder battery to fail and leak ?

In other words, are the powersounders failing because the main battery or charge is not adequately maintained ?

 :-?

[Marks DTM Calib]

Interesting one.

On the power sounder battery side of things, it will be very dependent on the charge circuit used.

If it is (and I know its not) a modern uber duper smart controler then it will keep it in tip top condition no matter what (as these can also boost volts using flyback on the switcher coils as well as reduce volts)

What I cant recall is the power sounder battery voltage (is it 6v in total ?).

If significantly lower then the car battery then it should be ok.

I would infer that the charge circuit in the power sounder is a pretty simple affair with I suspect nothing more than a constant V and I arrangement with the V regulation coming from the main circuit regulator and the I probably from a resistor!

A car battery generaly wont crank the car once its down to about 10.5-11V.

So it may well be not related.

THE most important part of any rechargeable circuit is the charger and the one in the power sounder (as per most domestic items) has been done very much at a cost (given the time when it was developed)

[Jimbob]

Interesting theory

when ours went, the thing had never made a single beep prior to the incident.  No warning whatsoever

The car had been stood for 24 hours odd prior to the fire.

The car battery was 11 or so volts when I checked it the next day (sure it was just under 12) :-/

http://www.omegaowners.com/forum/YaBB.pl?num=1259433462/0

[Dave DND]

The car battery was 11 or so volts when I checked it the next day (sure it was just under 12)

And that is EXACTLY my point . . .

Could the low voltage of the car battery have been a contributary factor in what happened next ?

 :-?

[Dave DND]

A car battery generaly wont crank the car once its down to about 10.5-11V.

But a battery at say, 11.5v would be enough to start the car, but would not be seen as adequate enough to keep the powersounder charged -

As you say, interesting theory . . . .

 :-?

[Marks DTM Calib]

A car battery generaly wont crank the car once its down to about 10.5-11V.

But a battery at say, 11.5v would be enough to start the car, but would not be seen as adequate enough to keep the powersounder charged -

As you say, interesting theory . . . .

 :-?

If we consider a battery at say 13.4V starts the car well then at 10.5V you only have 60% (it will actualy be worse than this as the internal resistance of a discharged battery rises) of the starter power.....and hence it more often than not wont start it.

Yet the power sounder battery may well still be fine (we need to find out how many V's it is) and charging ok.

What I infer may be happening is that the power sounder batteries are dying and maybe have a short circuit cell in them.....this then ups the charge current (on a basic charge circuit) and boils the others or cooks the onboard resistor.

It maybe worse than we originaly thought and the charge circuit could be so simple that there is actualy no voltage reg at all and it relies on the reality that the vehicle supply volts never goues about 14ish V's....and has only a series resistor (god help us!)

That would be bad in the case of an alternator reg failure resulting in high charge volts. 

[zirk]

No nothing about the power sounder back up supply, but whats the normal voltage of the PS Batteries?.

[Dave DND]

I`m thinking more along the lines of the main battery voltage being just a fraction lower than the voltage threshold set by the powersounder battery, and the main battery is now being seen as a LOAD that is draining the powersounder, albeit at a miniscule and insignificant current, but a load none the less.

Although probably in microamps, or the odd milliamp at most, would it be enough to cause the small powersounder battery to overheat and break down?

If it starts to overheat and boil, then the acid leaks, wrecks the board and eventually combusts, that bit we all know.

For a rechargeable battery to fail is pretty unusual, and because they have lasted a while, build quality can be almost (!) ruled out - also, If it was one type of sounder that failed, fair enough, but as there are several versions using different battery configurations and types, then surely it has to be something external to it, ie: the car !!

I`m more puzzled that this is fairly commonplace here, but problems are with both original and replaced batteries, so that leads me to beleive that its something we are either doing, or not noticing that is causing this powersounder to fail.

[Entwood]

Not sure if this adds anything or not ....

When my powersounder started to play up first indications were random alarms, followed within 48 hours by the infamous "beeps"on shut down.

I replaced the powersounder with a new one, this was May 09 so 14 months ago. The removed one was AFAIK original fit, so was 8 years old

False alarms stopped, and obviously, no beeps.

Battery is the same one , alternator has not been touched, car usage pattern is the same.

I've had no other electrical problems (touch wood) and the car electrical system works quite hard when towing as it runs the fridge in the 'van and the cool box on the rear seat .. and I've towed 18 weekends this year so far.

HTH

[Dave DND]

OK, for those of you who have been unfortunate enough to witness this first hand, some questions:

What time of year was it?
What time of day was it?
What was the weather / temperature?
Is the car used for long / short journeys?
When was the Battery last replaced?
Have you heard any "beeps" from the sounder?

As a guess, I bet that conditions were cold and the battery is a few years old - if so, this kind of adds weight to my theory as temperature can have quite an impact on battery voltage.

 :-?

[Dave DND]

Not sure if this adds anything or not ....

When my powersounder started to play up first indications were random alarms, followed within 48 hours by the infamous "beeps"on shut down.

I replaced the powersounder with a new one, this was May 09 so 14 months ago. The removed one was AFAIK original fit, so was 8 years old

False alarms stopped, and obviously, no beeps.

Battery is the same one , alternator has not been touched, car usage pattern is the same.

I've had no other electrical problems (touch wood) and the car electrical system works quite hard when towing as it runs the fridge in the 'van and the cool box on the rear seat .. and I've towed 18 weekends this year so far.

HTH

So it could be that the main battery takes a little while to break down the powersounder battery, and the problem is only noticeable on powersounder batteries that are past their best and now starting to deteriorate rapidly?

Batteries certainly don`t last forever, and it could be that your "new" powersounder batteries were in good enough condition to mask any faults for a few years to come?

 :-/

Or, of course it could be that you genuinely had a faulty powersounder ?

 :-?

[Entwood]

1) May 09
2) False alarms - Early Morning (around 2 am)
3) Can't remember but cool /damp I think
4) Good mixture of both
5) Over 2 1/2 years .. ie   not by me !!!
6) yes .. 48 hours after the false alarms started but only on switching off the engine - which I think was the PS complaining about a voltage drop as the charging circuit switched off.

PS was replaced   

I'm about to go out and put a multimeter on the system just to see what the readings are ... back shortly .

EDIT :

Car has not been started for  2 days :

Battery voltage before cranking = 12.09 v
Battery voltage @ 600 rpm  = 13.65 v
Battery voltage @ 2000 rpm. initially 13.89 but rising very slowly, after 2 minutes it was 13.96 and still rising (what I'd expect as the battery becomes charged - should top out at 14.3 if I left it long enough )

So I think the battery / electrical system is about right ... does that help at all ?

My personal take on the PS problem is that the batteries fail, possibly due to the "memory factor" of rechargeables, which all the stuff I've read says you should fully discharge a rechargeable every so often .. never happens to a PS battery (and I know that "rule" only applies to older rechargeables .. but thats whats in the PS) !!

Just my thoughts .. nowt else .... 

[Dave DND]

My personal take on the PS problem is that the batteries fail, possibly due to the "memory factor" of rechargeables, which all the stuff I've read says you should fully discharge a rechargeable every so often .. never happens to a PS battery (and I know that "rule" only applies to older rechargeables .. but thats whats in the PS) !!

Just my thoughts .. nowt else .... 

Battery readings would suggest to me that all is well with your car.

I understand where you are coming from with the memory effect, and I know that powersounders are never run down

However,

There are millions of rechargeable batteries in circulation, and if they kept spontaneously combusting, then someone would have noticed by now - and they would all have been withdrawn - and yet a fairly small group of people are experiencing an exceptionaly high percentage of failures - that does not seem to me like the battery failing, more like the circumstances under which its failing.

[Marks DTM Calib]

I susepct that its not the batteries actulay going up thats the issue.

I would think that it is either a failing battery over stressing a poorly designed charger circuit or the battery leaking and damaging components on the board.

There is certainly a diode in the circuit to stop the power sounder batteries from driving back out onto the vehicle supply.

Perhaps its time I cracked open the one on the shelf in the garage for a closer look 

[Dave DND]

I susepct that its not the batteries actulay going up thats the issue.

I would think that it is either a failing battery over stressing a poorly designed charger circuit or the battery leaking and damaging components on the board.

There is certainly a diode in the circuit to stop the power sounder batteries from driving back out onto the vehicle supply.

Perhaps its time I cracked open the one on the shelf in the garage for a closer look 

Good idea - if I had one here I would be doing the same

just a thought

wonder if that diode is ok, or leaky ?
If it was allowing current to flow in either direction, then theoretically it could cause the problem? 

I know I`m clutching at straws, but it would be good to get to the bottom of this one